Electric regenerative motor and system of control.



B. LUNDELL.

ELECTRIC REGENERATIVE MOTOR AND SYSTEM OF CONTROL,

APPLICATION FILED MAR. 13, 1911,

Patented Feb. Q, 1915.

4 SHEETS-SHEET l.

"11. LUNDELL.

ELECTRIC REGBNEBAIIIYVB MOTOR AND SYSTEM 0F CONTROL.

APPLICATION FILED MAR. 1.3, 1911,

LIQYFACQ, v Pmnea Feb. 9, 19m.

4 SHEETS-SHEET 2.

R. LUNDELL. ELECTRIC REGENERATIVE MOTOR AND SYSTEM OF CONTROL.

APPLIUATIQN FILED 111111.13. 1911.

Llf.. tented. 116.119.1915

4 SHEETS-SHEET 3 E. LUNDELL. ELEGTETG EETENEEATITE MoToE ATD SYSTEM 0E coNTEoL.

APPLICATION FILED MAR. 13, 1911. lplgD Patented Feb.9,1915.

4 SHEETS-SHEET 4.

ROBERT LUNDELL, OF NEW' YORK. N. Y.

ELECTRIC REGENERATIVE MOTOR AND SYSTEM OF CONTES".

Specification of Letters Patent.

Patented Feb. 9, 1915.

Application led March 13, 1911. Serial No. 613,957. y

To all 'whom it may concern.'

Be itknown that I, ROBERT LUNDELL, a citizen of the United States, and resident of New York, borough of Manhattan, county and State of New York, have made a new and useful Invention in Electric Regenerative Motors and vSystems of Control, of

which the following isa specification.

The present invention relates to improvements in separately excited motors or dynamos and in the series-parallel control of such motors or dynamos when used in connection with regenerative traction work or similar service.

The objects of the invention are-First, to provide novel means by which the characteristic of a separately excited mctornmay at will be changed into the characteristic of a compound wound motor or a series motor without-the aidv of additional excitation windings or other complications of the main motor windings. Second, to combine such novel'means for varying the characteristic of a separately lexcited motor--with a regenerative system of series-parallel control for two or more motors of the interpole or the compensated type, whereby superior re'-,

sults may be obtained in regard to eiiiciency, smoothness of acceleration or retardation, simplicity, and general reliability.

My invention' can best be described in connectionA with a 'type of motor which I of the drawings, all of which are diagramhave previously vdescribed in U. S. Patent No. 857,184, granted to me on the 10th day of June, 1907. Particular attention is called to Figure ,6 of the drawings of this patent and the description pertaining thereto, as the present invention is a direct improvement upon or an amplification of the apparatus disclosed by the said figure.

4My invention will best be understood by reference to the accompanying nine figures matic, and in which-- Fig. 1' indicates a single main motor and an independentor separate sourceof current supply'for the field excitation of the said'main motor, together with means for .regulating the rate and the character of the said excitation according to my present invention. IF ig. 2 shows the same main motor, as indicated in Fig. with a modification of the means employed for regulating the excitation of the said main motor. This ligure indicates alsol the method of reversing .thedirectionv of rotation of the main motor.

Figs. 3, 4 and 5 are vector diagrams which indicate the relative values-of the various 4field strengths in connection with the main motors and in which the individuak units i are arranged according to Fig. 1.9 Fig. 8 is substantialla7 the same as Figzx, .except that the individual units have been arranged according to Fig. 2. Fig. 9 indicates a switch or controller ar1..nged to effect the various circuit changes which are particularly shown in 'Fig S. Y

Referring now to the figures in detail- Fig. 1 shows a main motor M having a distributed field vwinding F and a distributed armature winding if., both windings beim.r of the same type,.tha\` is, either ring or'druni windings embedded in the iron according to usual practice. .The diagram illustrates a two-pole arrangement, but the actual, motor should for obvious reasons be'of a multipolar construction.

The windings arenso proportioned that the ampere-turns per pole in the field winding somewhat exceed.thercorresponding armature ampere-turns, so that, when these two windings, are connected in opposition, the dii'erence between rthe lrespective ampere-turns will produce a commutation lfield of the requiredjstrength. It will be noticed that the field winding .is furnished with four leads; two of these are used as a line current inlet for the purpose of producing a compensating field in opposition 4to the armaturev field. The other two leads. located Vat 90 electrical space degrees from the first mentioned leads'` are' connected to an independent source bitumen/t supplyvpreferably a smallflow toltage,giiztor-genI erator G'thes'o'le duty'lof which is .to furnish t'he'excitation current for the main motor. ,y

The arrangement sofar is identical 'with roe' that proposed in connectionwith Fig. 6 f

Hov

pensation, and a winding for commutation. It will be understood that the motor becomes a separately excited motor or a sepa-v vrately excited dynamo when the field termiistie is equal to that of a shuntwound or a' separately excited motor. Although such a motor is in no sense a compound-wound or a series motor, it becomes possible by the present invention to change its characteristic at will into that ot' a compound-wound or a series motor. This is accomplished entirely by external means or by furnishing the small generator G (the exciter) with both shunt and series field windings C and D, as clearly shown in Fig. l. It the said series field windings are included in the armature circuit of the main motor, as shown, it becomes evident that the characteristic of the main motor M may readily be varied to suit requirements. For instance, if the shunt field windings of the generator G are disconnected t'rom the power circuit and the series field windings alone ire in the main circuit-the characteristic of the main motor clearly becomes similar to that of a plain series motor. lf, on the other hand, the series field winding is short-circuited and the shunt field winding is connected to the power circuit, the characteristic becomes equal to that of a separately excited motor or a shunt motor. lVhen both of the field windings C and D are in service the characteristic of the main motor becomes similaito that of a compound-wound motor. Obviously this arrangement is exceedingly fiexible, and it is in addition simple and reliable because it avoids any complication in the windings of the main motor. The rate of excitation as well as the rate ofl compounding of the main motor may conveniently be regulated by the resistances R in- I eluded in the shunt field circuit 'of the gen-` eratou) G. These resistances are most con- Veniently manipulated by the aid of' a small rotary switch, of which the stationary and the movable contacts are clearly shown in Fig. l. This switch is also arranged to short-circuit the series field winding D and to disconnect the shuntwinding G oi the exciter G at certain positions of the said movable contacts, as indicated on the drawing. 4The rate .of excitation may also be regulated by resistances T included in the excitation circuit, as clearly shown in Fig. 2. In order to reverse the direction of rotation of'this type of motor it is merely necessary to reversethe current in the excitation windingas clearly shown in Fig, 2. yThe series field winding of the generator G-may only carry a portion of the current which traverses the armature of the mainmotor. It is, in fact, advantageous to divert part of the said current through an inductive resistance V E, as shown in Fig. 2, )rovided the same is diferentfield strengths (or the magneto motive forces) and the manner in which they vary according to the load andthe changes in the excitation. In these figures arepresents the armature field, r: the compensating and the commutating field, m the resultant field without including the armature reaction, n the resultant field including the armature reaction, and o represents the commutation field. Fig. 3 shows the conditions resulting from full. field excitation and normal full load armature current. Fig. 4 illus trates full excitation and half load. Fig. 5 shows reduced field excitation vin connection with 50% overload.

The results obtained in connection with the above mentioned single distributed field winding are identical with those Obtained in connection with Fig. 6, wherein the field winding is illustrated as having been split up into two distinct distributed windings, one for compensation and commutation next to the armature winding) and another for excitation, each of said windings being represented by a heavy circle in the diagram. This figure is merely shown for the sake of comparison. It will be understood that a motor constructed according to the arrangement shown in Fig. 6 would have very much more copperI and greater dimensions, besides being more complicated. The

compensating and the c'ommutating Winding alone must clearly be equal to the single winding F shown in Figs. l and 2, if the etliciency is to be the same, and the separate excitation Winding will, of course, re-

.quire a great amount of. additional copper and additional room.

Fig. 7 illustrates diagrammatically, in a system of. series-parallel control, the suc* cessive changes in the circuit connections of a pair of mechanically connected regenerative traction motors arranged according to Fig. l. M1 and Mz represent the main motors and G1 and G2 the small generators for energizing the fields of the separately excited main motors. respectively, the series field windings, an

@1 and C2 the shunt field windings of the small generators- P represents the usual D1 and D2 representA Lian-ies 8 the starting resistance is in circuit. TheV motors are at the same time receiving their maximum excitation current because the field magnets oli-G1 and G2 are 'fully energized from both the shunt and the series field windings, as clearly shown in the diagram. 4

In Diagram Z) a portion of the starting resistance is cut out. Between b and the Working position indicated by Diagram 1 .the last portion of the starting'resistance hasheen cut out and the series field Windings D1 and D2 have subsequently become short-circuitcd by the controller. The field excitation of the main motors has, therefore, been somewhat reduced in Diagram 1. There is in this diagram onl a slight'difference between the motor-speeds and the corresponding dynamo-speeds because the main motors are non' Working Wit-h characteristics similar to shunt motors operating without external armature resistance.

In the working position indicated by Diagram 2 the shunt excitation of the generators G1and G2 has been somewhat reduced and thewmain motors have, consequently, increased their speed. If the torque of the main motors is to remain constant the armature current will, of course, increase in proportion to the reduction in the field strength-same as for any adjustable speed motor. Diagram 3k shows the main motors working under an additional reduction of field excitation and their speed has, of course, been correspondingly increased.

IVe lwill now assume that the field strength of the main m'otors is about onehalf of the field strength during the starting pc tions a and b@ Each motor consumes, rcourse, one-half of the line voltage and the torque of each motor is the same las in Diagram mor b, provided the armature current has been doubled.

'ln the transition position indicated by Diagram c the field excitation of motor M1 hassuddenly been restored to a full maximum andthe field excitation of motor M2 has simultaneously been reduced to zero, the excitation circuit from the generator G-2 y having been opened, as clearly shown in the diagram. This causes the motor M1 to consume nearly the full hne voltage, Whereas motor M2 only consumes a small amount of the line voltage due to the internal resistances of the armature and the compensating windings. Motor M1, furthermore. carries thel entire load, which it can do without being over-loaded, because its torque with maximum field strength is equal to the combined torque of both motors in Diagram 3, provided the current through the armature circuit remains the same as in Diagram 3. Motor M2 clearly produces no torque, but runs along at the same speed, being mechanically connected to M1.

In the transition position cl motor M2 has been short-circuited with zero field excita-l tion and motor M1 is-noW receiving the full line voltage. The speed is, consequently, a trifle greater than in Diagram c. In transition Diagram c the motor M2 vis'merely disconected from the -lline and made ready to be connected in parallel with motor M1. It will be noticed that the series field Windings of G1 and G2 have been connected in circuit during the transition steps'c, el, and

e. The motor which carries the load will, therefore, act as a compound-Wound motor durinof acceleration and asa differentially wound generator during retardation. That `ris, it will in either case .have the proper drooping characteristic which insures smooth acceleration or retardation.

Diagram 4 illustrates the first Working position when the motors are in parallel. If the total current from the line remains the same as in Diagram e, it follows that each motor will againconsume one-half of this current or about the same current as in the starting position a orb. The series field Windingsrof the generators G1 and G2 being included in their respective armature circuits vof the main motors, it follows that the main motors will thereby be given a certain self-regulating quality, which in turn Will insure a proper division of the load. In the following Diagrams 5, 6, 7 and 8 the shunt excitation of the generators G1 and G2 is successively reduced and the speed of the main motors increased. In the final-working position 8 the shunt excitation of the generators G1 and G2 has been'very much reduced and the excitation from the series field windings 1s, of course, considerable,

because the current in the armature circuits of the main motors has increased as the field strength has been reduced.- The main motors will, therefore, havev` characteristics similar to compound-wound motors having strong seriesand comparatively Weak shunt-field windings. Such a characteristic will in turn produce a very Wide difference` ing under light loads, such a modification 'between the motor speeds and the dynamo speeds for this positlon.

may best be accomplished by keeping the shunt excitation of the generators G1 and G2 const-ant and by regulating the field strength of the main motors according to the method shown in Fig. Q.

Fig. 8 illustrates such a Amodilication of the regenerative system ot control described above. As each individual diagram of Fig. S corresponds with the diagrams of Fig. 7, when the indexes are the same, a minute description of Fig. 8 would merely amount to a repetition ot' previous remarks, and it is, therefore, omitted. Diagram a of Fig. 8 shows the shunt field windings of the generators G1 and G2. As there is no `change in the shunt excitation of G1 and G2 during the various steps the said shunt field windings have been omitted in 'the subsequent diagrams.

Fig. 9 illustrates a switch or controller o't' ordinary construction together with all of the circuit connections between the stationary contacts of the said controller, the line l circuit, a` pair of main motors M1 M2, a pair of exciters G1 G2 with their 'series and shunt field windingsD1 D2 and C1 C2, starting resistances P and lspeed regulating resistances T1 T2, said controller being designed to cliect the various circuit changes (a to S) which are particularly,shown in Fig. 8. The left hand portion of Fig. 9 illustrates, according to the usual practice, the development of the movable contacts of the said controller, which etfect (at the positions a. to 8) the corresponding circuit changes illust-rated in Fig. 8. The right hand portion of Fig. 9 illustrates ina similar manner the developed movable contacts of a switch for reversing the direction o t` rotation of the main motors M1 M2, said switch being also arranged to serve as a. starting switch :tor the motor which drives the exciters G1 G2, as clearly shown on the drawing.

Having thus described my invention what 'l claim and desire to secure by Letters Patent of the United States isl. An electric motor having a single tieldV winding for excitation connected to a separate source of current supply, said source of current supply being provided with means for changing at will the characteristic of'the said motor to resemble the characteristic of either a shunt-Wound motor, a compound-wound motor, or a series motor.

2. A separately excited motor having a single distributed field winding for excitation and for compensation. in combination with external means for changing at will the characteristic of the said motor to resemble the characteristic ot compoundwound motor. or a series motor.

jA dynamo electric machine having a single distributed ield winding for excitation and for compensation connected to a separate source of current supply, said separate source ot' current supply being provided with means 'for giving the said dynamo electric machine a characteristic similar to that of a compound wound machine; in combination with additional external means :tor rai-ying at will the percentage ot' the compounding ot the said dynamo lelectric machine.

l; Two or more separately excitedmotors in combination with means for changing the E. M. F. impressed upon the individual armature-circuits and additional means for changing at will the field excitation of the motors so that the same becomes more or less dependent upon the armature current or the load.

5. T wo or more motors having each a single distributed field winding for excitation and for compensation, in combination with a source ot independent current supply for each lield winding, means for connecting the motors in series or in parallel, and additional means for changing at will the field excitation of the motors so that the same becomes more or less dependent' upon the armature current or the load. u

(l. The combination'ot' a plurality of separately excited motors, a controller for con` necting `them in 'series or in parallel, exter-, nal means t'or'regulating the excitation ot' the motors according to the desired1 speed changes. with additional external means for automatically varying the excitation according to the changes in the load.

The combination of a pail" of separately excited motors having theirgexcitation-lield windings connected to independent sources ot' current-supply, i; controller for connecting the motors in series or in parallel, means for keeping the current from a power circuit closed through one of the motors during the change from series to parallel or from parallel to series, vwith additional means for short-circuiting the other motor with substantially zero field excitation during the aforesaid change from series to parallel.

8. The combination of a pair of mechanically connected motors having each a single distributed eld winding for excitation and for compensation, a source of independent current supply forl each field winding adapted to give to each motor an independent excitation, means for connecting the motors in series or in parallel, with additional means for keeping one of the motors operatively connected in a power circuit While the othermotor is idle during the change from series to parallel or from parallel to series.v

9. The combination of a pair of mechanicall)v connected motors 4having each a single distributed field winding for excitation and for compensation, asourc'e of independent current supply for each eld winding' adapt-- ed to give to each motor an independent eX- citation, mea'nsfor changing the E. M. F. impressed upon the individual armatureircuits, with additional means for regulating the strength of one motor independently of -the other motor, so that one motor may control the speed and carry the load while the E. M. F. impressed upon the armature-circuit of the other motor is 1o being changed. l

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses. 1

ROBERT LUNDELL. Witnesses:

C. J. KINTNER, M. FIKEATING.

copies ot this patent may be obtained for ve cents eac-h, by addressing the Commissioner of llatents,

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